Poiseuille’ s Formula
The rate of flow( v) of liquid through a horizontal pipe for steady flow is given by
where, p = pressure difference across the two ends of the tube. r = radius of the tube, n = coefficient of viscosity and 1 = length of th tube.
The Rate of Flow of Liquid Rate of flow of liquid through a tube is given by v =( P / R) where, R =( 8 ηl / πr 4), called liquid resistance and p = liquid pressure.( i) When two tubes are connected in series Resultant pressure difference p = p1 + p2
Rate of flow of liquid( v) is same through both tubes. Equivalent liquid resistance, R = R1 + R2
( ii) When two tubes are connected in parallel 1. Pressure difference( p) is same across both tubes. 2. Rate of flow of liquid v = v1 + v2 3. Equivalent liquid resistance( 1 / R) =( 1 / R1) +( 1 / R2) Stoke’ s Law
When a small spherical body falls in a long liquid column, then after sometime it falls with a constant velocity, called terminal velocity. When a small spherical body falls in a liquid column with terminal velocity then viscous force acting on it is
F = 6πηrv